This invention concerns systems and methods for laminating and removing films. More particularly, the present invention provides an integrated film lamination and removal system and methods of using the same.
Adhesive coated films are often used or applied to a variety of surfaces for reasons such as advertisement, decoration, protection, etc. In some instances these films may be used in place of painting to protect surfaces or to provide a uniform appearance, such as to a fleet of trucks. Regardless of their specific use, these films, which are often exposed to environmental conditions, have a finite life and must be removed prior to replacement.
The lamination of films often requires that pressure be supplied to force the film against a substrate to which it is to laminated. The substrate to which the film is to be laminated may be another film, a fabric, a structure (e.g., the side of vehicle, a wall, etc.) or any other object. The films are often coated with an adhesive to adhere the film to the substrate, but lamination of the adhesive-coated film under pressure often assists in providing a more secure bond between the film and the substrate. The use of pressure may also provide other advantages, e.g., reducing bubble formation, improving conformity, etc.
Although it is desirable to use pressure when laminating a film to a substrate, it can be difficult to provide enough pressure to effectively influence the lamination process. For example, when laminating two films to each other over, e.g. a roll structure, allowances must be made for deflection of the rolls because the lamination force can typically be applied only at the ends of the rolls. The result is that the size and weight of the rolls and supporting structure may be massive to compensate for roll deflection while generating sufficient and uniform pressure at the lamination point.
Another example can be found in the application of adhesive-coated plastic films, especially vinyl films, to a variety of surfaces for a variety of reasons such as advertisement, decoration, protection and the like. These surfaces can be very large in area, typically as much as 3 mxc3x9716 m. These films are adhered to very large horizontal or vertical surfaces such as walls, truck trailer sides, billboards, and the like. The films are seldom large enough to cover the entire surface with a single, integral film, so multiple films are typically used. In addition, attempts to make larger films result in films that are more difficult to handle and to register to other films. These surfaces have vast even and uneven portions, such as a truck trailer side that has flat surfaces interrupted by either corrugations or rivets, or both. These surfaces with some combination of flat portions, protrusions, and indentations require very skilled persons to adhere the film to the surfaces and then assure that such film adheres also to the protrusions or indentations, or both.
In the most common methods of applying these films to, e.g., truck trailers, a small plastic squeegee approximately 10 cm long is typically used to manually force the film against the substrate. This is a very labor intensive process. Furthermore, this application requires skill and patience to get an application that is well adhered, free of wrinkles, and in which all films are in register.
Removal of these adhesive coated films also presents difficulties due to the size of the films. The adhesives used to apply the films to the substrates also typically have a relatively high adhesion, making their removal somewhat difficult. Removal is currently accomplished by hand with an individual attempting to pull the film off of the substrate. It is difficult, if not impossible, for an individual to exert sufficient force to remove the entire sheet of film across its width at the same time.
As a result, the individual may be forced to remove small sections of the film, with the film often breaking during removal because of the forces concentrated at the removal location. To assist with removal, many individuals often cut the film into strips while on the substrate and remove the strips individually. Drawbacks to this approach however include the potential for damage to the underlying substrate as well as the additional labor required to cut the film prior to removal.
The present invention provides a vacuum-assisted film laminating and removal systems and methods of using the same. The systems include a vacuum-assisted laminator for applying large format films to substrates where lamination pressure is generated at least partially by a vacuum drawn in a vacuum cavity. The removal apparatus applies tension over the width of the adhesive film, thereby removing the film from the substrate along the release line that extends over the width of the film. The methods and apparatus are particularly useful in removing large-scale films from substrates such as truck trailers, vans, walls, signs and other large surfaces.
The systems and methods may be particularly useful to assist in the application and/or removal of adhesive-coated plastic films, particularly vinyl films, to large area surfaces to provide improved appearance, durability, etc. Some of the most common surfaces include truck sides, walls, signs, portions of a building, vehicles, etc. These large surfaces require extensive time and labor for application of films. This often adds more cost to the project that does the film itself. Furthermore, many of these applications are on surfaces that contain compound-curved protrusions or indentations such as channels or rivets or other irregularities that increase application time and often produce wrinkles.
The present invention uses the force generated by a partial vacuum at the interface of application, to adhere adhesive-coated films to large area surfaces. The technique is also especially effective on smaller, irregular surfaces.
Even when applied with a vacuum-assisted laminator, accurate alignment of the laminator relative to the substrate to which a film is to be applied may be important. The present invention also can provide steering systems that can be used to control the vertical position the laminator, distance between the laminator and the substrate, and can also move the laminator along the substrate in a desired direction.
In one aspect, the present invention provides a film lamination and removal system that includes a laminator having spaced-apart first and second laminating rolls mounted parallel to each other, a seal mechanism extending between the first and second rolls, wherein the seal mechanism forms a seal with each of the first and second rolls, a vacuum cavity formed between the seal mechanism and the first and second rolls, and a vacuum port in fluid communication with the vacuum cavity. The system further includes a removal apparatus operatively coupled to the laminator, the removal apparatus including a winding roll attached to a frame, and a motor operably connected to the winding roll for rotating the winding roll about its longitudinal axis.
In another aspect, the present invention provides a method of using a system such as that described in the preceding paragraph to laminate an adhesive film to a substrate. The method includes locating the system proximate a substrate, wherein the substrate further defines the vacuum cavity; locating an adhesive film between the substrate and at least one of the first and second laminating rolls; drawing a vacuum through the vacuum port, wherein a negative pressure is provided in the vacuum cavity and wherein the first and second laminating rolls are drawn towards the substrate; and moving the system along the substrate in a lamination direction, whereby the adhesive film is laminated to the substrate.
In another aspect, the present invention provides a method of laminating and removing adhesive films from a substrate. The method includes providing a film lamination and removal system that includes a laminator having spaced-apart first and second laminating rolls mounted parallel to each other, a seal mechanism extending between the first and second rolls, wherein the seal mechanism forms a seal with each of the first and second rolls, a vacuum cavity formed between the seal mechanism and the first and second rolls, and a vacuum port in fluid communication with the vacuum cavity. The system further includes a removal apparatus operatively coupled to the laminator, the removal apparatus including a winding roll attached to a frame, and a motor operably connected to the winding roll for rotating the winding roll about its longitudinal axis. After providing such a system, the method includes locating the system proximate a substrate, wherein the substrate further defines the vacuum cavity; applying tension to a first end of an existing adhesive film adhered to a substrate over the width of the existing adhesive film to remove the existing adhesive film from the substrate along a release line; distributing the tension on the substrate in the form of a compressive force; advancing the release line and the compressive force towards a second end of the existing adhesive film, whereby the existing adhesive film is removed from the substrate; locating a new adhesive film between the substrate and at least one of the first and second laminating rolls; drawing a vacuum through the vacuum port, wherein a negative pressure is provided in the vacuum cavity and wherein the first and second laminating rolls are drawn towards the substrate; and moving the system along the substrate in a lamination direction, whereby the new adhesive film is laminated to the substrate.
One feature of the present invention is the laminator which utilizes a partial vacuum, also known as negative pressure, in a vacuum cavity of the laminator to generate pressure on the laminator at the interface between the laminator and the substrate where a film is subsequently laminated. The resulting lamination pressure is essentially uniform across the lamination area because the negative pressures within the vacuum cavity are substantially equal.
When used to apply graphic images and other films to, e.g., trucks, other vehicles, sign surfaces, buildings, etc., one advantage of the present invention is labor savings of such significance that the overall total cost of an adhesive film applied to a large vertical or horizontal substrate, especially one having multiple compound or irregular surfaces can be substantially reduced. Furthermore, the quality of application is significantly improved, and often, lower adhesion adhesives can be used which reduce removal time. Even with the cost of film remaining constant, the labor savings reduces the total cost of application of the film by as much as 80%.
When, in conjunction with vacuum, heat is used in the lamination process, the conformability of the film around irregular or compound-curved surfaces is improved such that less aggressive adhesives can be used. These adhesives, often called removable or changeable adhesives, can save 80% of the time normally associated with removal of adhesive films. This can further cut the total cost of installed and removed applied films by as much as 60%.
With these substantial labor savings using the article and method of the present invention, one company can provide an entire product of both film goods and installation/removal services at a price considerable less than currently offered where the producer of the film goods and the installer of the film goods are unrelated companies.
Another advantage of the invention is that large sheets of film can be laminated to surfaces at high productivity of speed and assured lamination.
Another advantage of the invention is that the laminator can provide nearly 100% wetting area of the adhesive against the surface of the substrate whereas conventional squeegee usage can only achieve about 80% wetting. The use of a partial vacuum uses the power of a fluid to apply equal pressure at every point of contact of the film to the surface, something that is extremely difficult, if not impossible, to achieve when applying pressure with a device such as a squeegee. That advantage is even more apparent with surfaces that are filled with irregularities or compound curves or both.
The systems and methods of the present invention may also be used to remove existing laminated films. Films laminated by vacuum-assisted laminators may be even more difficult to remove by hand, thereby making use of the present invention with its integrated removal apparatus even more advantageous.
When used in connection with a vacuum-assisted lamination system, it may be preferred to mount the film removal apparatus of the present invention ahead of the laminator, thereby providing an integrated system that can be used to remove an existing adhesive film from the substrate and replacing it with a new film in one pass. Such an integrated system may also take advantage of the steering and other features provided with the lamination systems.
The systems of the present invention may also be used in combination with the vacuum-assisted adhesive film laminating apparatus disclosed in U.S. patent application Ser. No. 09/236,806 filed on Jan. 25, 1999 titled INTERSECTING HEAT AND PRESSURE FILM APPLICATOR AND METHODS OF USING SAME and U.S. patent application Ser. No. 09/479,648 filed on Jan. 7, 2000 titled METHOD OF APPLYING ADHESIVE COATED FILM.
The tension applied to the adhesive film during removal is preferably uniform across the width of the film, thereby reducing the risk of the film tearing or breaking during removal. The release line is advanced during removal along the length of the film until the entire film is removed from the substrate.
One removal apparatus for removing adhesive films according to the present invention includes a roll that is operably connected to a winding mechanism that can supply adequate torque to remove the adhesive film from the substrate. The winding mechanism may include a torque limiter to reduce or prevent the likelihood of breaking the film during removal. Power for the winding mechanism may be provided by any suitable device, e.g., electric motor, air motor, hydraulic motor, etc.
Optionally, it may be desired to distribute the tension forces applied to the film back to the substrate in the form of a compressive force with the compressive force being applied to the substrate proximate the release line. The compressive force may be applied by any suitable structure, although a roll is typically preferred to avoid damage to the underlying substrate.
The tension forces may not need to be applied back to the substrate where the film removal apparatus itself is sufficiently rigid and robust to withstand the tension applied during removal of the film.
The systems and methods may be particularly useful to assist in the removal of adhesive-coated plastic films, particularly vinyl films, from large area surfaces after the films have reached the end of their useful life. Some of the most common surfaces include truck sides, walls, signs, portions of a building, vehicles, etc. Extensive time and labor may be required to remove adhesive films from these large surfaces.
It may be preferred that the systems and methods of the invention be used in connection with the application and/or removal of large-scale adhesive films from substrates. For the purposes of the present invention, a xe2x80x9clarge-scale adhesive filmxe2x80x9d is a film having a width of 70 centimeters or more and a length of 2 meters or more.
As used in connection with the present invention, the term xe2x80x9cvacuumxe2x80x9d is used to describe negative pressure as compared to ambient pressure. The term does not require that an absolute or extremely negative pressure vacuum be drawn or maintained, although in some instances it may be possible and/or desirable to achieve large negative pressures in connection with the present invention.
Other features and advantages will be described below using the following drawings.